This invention relates to a a multistep process for the production of a gasoline boiling range fuel component comprising monoaromatic hydrocarbons. More specifically the process of the invention comprises a process for upgrading a low value fraction from the cracking of carbometallic residual hydrocarbon oil to high octane gasoline.
Ashland Oil, Inc.'s new heavy oil conversion process (RCC.SM. Process) has been described in the literature (Oil and Gas Journal, Mar. 22, 1982, pages 82-91), NPRA paper. AM-84-50 (1984 San Antonio) and in numerous U.S. patents assigned to Ashland Oil, Inc., for example U.S. Pat. No. 4,341,624 issued July 27, 1982 and U.S. Pat. No. 4,332,673 issued June 1, 1982. These disclosures are incorporated by reference in the present disclosure.
Briefly, the RCC Process is designed to crack heavy residual petroleum oils that are contaminated with metals such as vanadium and nickel. The feedstock to the until will have an initial boiling point above about 343.degree. C. (650.degree. F.), an API gravity of 15-25 degrees, a Conradson carbon above about 1.0, and a metals content of at least about 4 parts per million (PPM). The hot feed is contacted with fluid cracking catalyst in a progressive flow type elongated riser cracking tube and the cracked effluent is recovered and separated.
One of the fractions recovered from the main fractionator is a light cycle oil (LCO) boiling in the range of from about 216.degree. C. (430.degree. F.) to about 332.degree. C. (630.degree. F.). This fraction is not suitable as a motor fuel component because it contains a high proportion 10-60 vol. %, more typically 20-40 vol% of dual ring (bicyclic) aromatic hydrocarbons i.e. naphthalene and methyl and ethyl naphthalenes.
Because of the refractory nature of the LCO it cannot be recycled for further cracking in the RCC Process, nor can it be converted in a conventional fluid catalytic cracking (FCC) unit.
The object of this invention is to provide a process for upgrading the LCO fraction to a high octane aromatic gasoline component.